How Do Breathalyzers Work, and Where Is the Technology Headed?

If you’ve ever been pulled over by a cop on suspicion of DUI, chances are you have been asked to submit to a breathalyzer test. This small device presumably (magically?) somehow measures the alcohol content in your blood by analyzing your breath, and whatever it reveals may influence the officer’s decision whether or not to arrest you.

But what, exactly, is the breathalyzer measuring? Is the reading accurate? What are your rights if an officer asks you to blow into a breathalyzer? Are these devices a truly effective deterrent against DUI? Let’s take a closer look at this technology—how it works, how it is used in real-life contexts with police, and what the future may hold as the technology develops.

How Alcohol Is Detected through Your Breath

Of course, if someone has been drinking, you can usually smell it on his breath—but that sensation is highly subjective and doesn’t tell you how much that person has had to drink. Breathalyzers don’t “smell” your breath—they analyze the presence of alcohol in your breath at the molecular level. Here’s how it works.

Alcohol molecules are small and can easily through the various membranes in your body—which is part of why alcohol can affect you within minutes after taking that first drink.

As HowStuffWorks explains, alcohol doesn’t get digested or changed as it enters the stomach, but instead it quickly gets absorbed into the bloodstream. When the blood travels through the lungs, some of the alcohol evaporates into your breath and is exhaled out the mouth. This is why when you breathe into a breathalyzer, the device can detect actual amounts of alcohol in your breath (not just the scent of it). The breathalyzer can then provide a mathematical estimate of how much alcohol must be in your blood to produce those concentrations in your breath.

How Breathalyzers Work

Most breathalyzers calculate blood alcohol content (BAC) using one of three technologies, producing results with varying accuracy:

• Semiconductor sensor technology—These relatively inexpensive breathalyzers use a low-voltage metal oxide semiconductor to oxidize alcohol molecules as you breathe into the device. These oxidized molecules affect the electrical current, and those changes are measured to calculate the BAC. Semiconductor breathalyzers often yield false positives if other substances are present, but these devices work fine for personal and home use (for example, to measure one’s BAC before getting behind the wheel).

• Fuel-cell technology—The breathalyzer type most commonly used by police for roadside testing, these devices work similarly to semiconductor sensors in that the fuel cells oxidize the alcohol and measure the resulting electrical charge. However, fuel cell breathalyzers are alcohol-specific and more reliable, so false positives are far less likely to occur.

• Infrared spectronomy—These larger, pricier units measure alcohol content by passing the breath through infrared light. The alcohol molecules absorb the light in a specific way so they can be identified and measured. You’re more likely to find an IR breathalyzer in a police station, to be used after you’ve already been arrested.

Are Breathalyzers Accurate?

At this time, blood tests are still the most reliable method for measuring BAC; home breathalyzers are good for providing reasonable estimates, while the roadside devices used by police are considered a bit more reliable. However, these breathalyzers still have a margin of error, which is why roadside breathalyzer results can’t be used as evidence if you are charged with DUI. Rather, officers only use them to evaluate whether there is probable cause to arrest you for DUI—which is why roadside breath tests are also voluntary.

Looking to the Future

As technology naturally evolves, developers continue to enhance and improve breathalyzers, releasing newer devices with greater levels of accuracy. Whether they will ever be accurate enough to be admissible in court remains to be seen. However, recent advances suggest we’re likely to see the use of breathalyzers expand beyond roadside alcohol testing into other applications. Let’s just explore a couple of examples.

Marijuana Breathalyzers

Driving under the influence of marijuana or other drugs carries the same penalties as alcohol-related DUI, but detection standards for THC (the drug in marijuana) have been inconsistent and confusing at best. However, according to U.S. News & World Report, several companies have developed breathalyzers to detect marijuana, and several of these products will be available on the market in 2018.

While we don’t know how accurate these devices will prove to be, experts suggest breathalyzers may actually become a more effective detection solution for pot than blood/urine testing, since those can detect the presence of THC but are less effective in measuring how much of the drug is present, or how long it has been in the person’s system.

In-Vehicle Breathalyzers

More and more, breathalyzer technology is being used as preventative measure against DUI, not just a detection method.
Ignition Interlock Devices are already in use in many parts of the nation to prevent repeat DUI offenses. These devices include a breathalyzer inside the vehicle, and the car simply won’t start if the breathalyzer detects a minimal alcohol content. Many counties (including Los Angeles County) require people convicted of DUI to have these devices installed on any car they own. However, as Big Think reports, we may actually start to see IIDs installed as standard safety features in new vehicles within the next decade or so.

Speaking of prevention, breathalyzers can be friend rather than foe. You might be intimidated by the idea of a cop asking you to take a breath test, but, as mentioned earlier, personal breathalyzers are available on the market right now, and using one, before getting behind the wheel, could save you from making a very bad decision. If you do find yourself arrested and charged with DUI, we can help. Give our offices a call as soon as possible.